Oh, I had two just like those once Only that mine were a different species xD Mine were three-lined corydoras (where the spots shape into a line on the side) while yours seem to be Harald Schultz's Corydoras

The Corydora Haraldschultz do have dark spots on a light body. Ours do have light spots on a dark body which is the Corydora Sterbai.Those two are very easy to confuse with each other. The Sterbai is more rare than the Haraldschultz one.